Hello All, I have a 1500mmx1500mm workbee from [fake china knockoff company] . I just finished the mechanical and electrical setup with the blackbox and I'm experiencing some very odd behavior along the y (and sometimes x) axis. The stepper motors seem to catch/slip/grind/jerk/chatter; not sure what the right term is. But it seems like there is a lot of torque/tension. The problem gets worse when I increase the maximum rates and the acceleration. When I drop the maximum rate to at or below 2500 mm/min, the problem seems to go away. Attached is a video. Can anyone guide me on what might be happening here and what I can do fix the chattering? I'd like to be able to run my machine faster than 2500 mm/min. Here are my grbl settings: $0=10 ; Step pulse time, microseconds $1=255 ; Step idle delay, milliseconds $2=0 ; Step pulse invert, mask $3=5 ; Step direction invert, mask $4=1 ; Invert step enable pin, boolean $5=0 ; Invert limit pins, boolean $6=0 ; Invert probe pin, boolean $10=1 ; Status report options, mask $11=0.020 ; Junction deviation, millimeters $12=0.002 ; Arc tolerance, millimeters $13=0 ; Report in inches, boolean $20=0 ; Soft limits enable, boolean $21=0 ; Hard limits enable, boolean $22=0 ; Homing cycle enable, boolean $23=3 ; Homing direction invert, mask $24=100.000 ; Homing locate feed rate, mm/min $25=1000.000 ; Homing search seek rate, mm/min $26=250 ; Homing switch debounce delay, milliseconds $27=5.000 ; Homing switch pull-off distance, millimeters $30=1000 ; Maximum spindle speed, RPM $31=0 ; Minimum spindle speed, RPM $32=0 ; Laser-mode enable, boolean $100=53.333 ; X-axis steps per millimeter $101=200.000 ; Y-axis steps per millimeter $102=200.000 ; Z-axis steps per millimeter $110=10000.000 ; X-axis maximum rate, mm/min $111=3000.000 ; Y-axis maximum rate, mm/min $112=2500.000 ; Z-axis maximum rate, mm/min $120=150.000 ; X-axis acceleration, mm/sec^2 $121=75.000 ; Y-axis acceleration, mm/sec^2 $122=150.000 ; Z-axis acceleration, mm/sec^2 $130=824.000 ; X-axis maximum travel, millimeters $131=1280.000 ; Y-axis maximum travel, millimeters $132=122.000 ; Z-axis maximum travel, millimeters $I=workbee1510
Are all the axis the same type of screw? the x isn't setup correct for 8mm lead screw like Y and z is. should be 200steps per mm like the rest.. also 10000mm/min is too fast. The problem is typical of speed or acceleration set to high. you can try increasing your current a bit to see if this helps as well. Your acceleration isn't set to high. Try all your max rates to 3000 to start with. Cheers Gary
thanks Gary. All axis are the same type of screw. I’ll adjust to 3000 mm/min or below. Is 10,000 is too fast, why is that the default setting? Is that something I can achieve by making modifications? I read about adding locktite to the couplers and and lead screw. It seemed like the frame not being square was also a potential issue. And the fact the issue only happens at the edges no matter how long I jogged made me think it had something to do with the frame positioning.
2500 axis speed is a decent starting point. I'm not sure what benefit there is in very fast axis rates because you would have to drop your cut depth to counter the higher forces and make more cuts.
Work on getting everything square for sure.. Make sure nothing is binding or wheels too tight against the rails, should be able to slip the wheels with your thumb at any point. Default grbl? maybe, but belt machines can do 10000mm/min so many default settings are not for your machine. Loctite on couplers is a good idea but probably not the cause of this issue. Set the anti backlash nuts only snug enough to get rid of backlash but not drag on the screw (practically no force on the set screw when new). Turn up the current (careful on the pots! try 75% of full) on the BB using the current adjust pots, you have high torque motors I presume? You are using a good 24V psu? check the voltage at the BB plug. Cheers Gary
With those high inductance motors from the Knockoff supplier, might even stall out at lower still than 3000. Probably more like 1500 max reliably Order our motors to get to 4000-6000mm/min
